A liquid crystal projector or other projection type display apparatus separates light emitted from a light source into red, green, and blue, modulates the colored light by three light valves each constituted by a liquid crystal display device (hereinafter referred to as an “LCD”), combines the modulated colored lights again, and enlarges and projects the same onto a projection screen.
As a light valve mounted in a liquid crystal projector etc., generally use is made of an active matrix drive type LCD using a thin film transistor (hereinafter referred to as a “TFT”) drive.
Almost all active matrix drive type LCDs use nematic liquid crystal. As the main display system, there is an optical rotation mode LCD.
The nematic liquid crystal used in an optical rotation mode LCD is a twisted nematic (TN type) liquid crystal having a molecular orientation twisted by 90 degrees and in principle gives a high contrast ratio and a good gray-scale display property in monochrome display.
For uniform display of active matrix drive type LCDs, it is necessary to uniformly orient the liquid crystal molecules on the entire substrate surface.
In substrates formed with two electrodes formed with alignment films, the alignment films of the substrates are arranged facing each other. In the seal region located around a pixel display area in which an image is actually displayed, the substrates are bonded to each other by a sealing material. In order to control the gap between the substrates, use is made of spherical spacers called “micro pearls” before the above bonding or use is made of columnar spacers formed by a resist.
By going through these processes, empty cells are produced. Thereafter, a liquid crystal is sealed in the empty cells whereby liquid crystal cells are formed.
Note that the above liquid crystal is comprised of several types of single liquid crystal materials and is also called a “liquid crystal composition”. Polarizers are attached to the produced liquid crystal cells whereby the liquid crystal display device is completed.
In these liquid crystal panels, at the time of the formation of the seal, if portions of the alignment films and the seal are superimposed on each other, the shielding property is lowered, the seal peels off, and other problems arise or moisture invades the liquid crystal through the interface between the alignment films and the seal to cause deterioration of the liquid crystal and other problems. Particularly when forming the films by spin coating, the films are formed up to the ends of the substrates, so the problems occur in a remarkable manner.
Further, in a projection type LCD used in a projector, since the image is projected enlarged, abnormalities in image quality easily stand out. Further, the amount of the light striking the panel is very large in comparison with a direct view type, therefore the panel becomes a high temperature, and deterioration due to entry of a minute amount of moisture is again easily seen.
In order to solve these problems, for example, the method of stopping the entry of moisture by adding a filling agent called a “filler” into the sealing material has generally been used (see for, example, Patent Document 1 and Patent Document 2).
In the LCD of Patent Document 1, a filler with a mean particle size of about 2 μm is added for the purpose of adjusting the viscosity of the seal.
Further, in the LCD of Patent Document 2, conductive beads of 6.0 μM or 6.5 μm are mixed in as conductive materials, and a conductive filler having a mean particle size of 0.1 to 0.5 μm is added in order to obtain conduction between facing electrodes via the conductive beads.
Patent Document 1: Japanese Patent Publication No. 11-15005
Patent Document 2: Japanese Patent Publication No. 11-95232